Microfluidic technology has been applied to expanding fields of research and analysis in an effort to increase speed, efficiency and accuracy of that research. Typically, microfluidic systems have at their core a microfluidic device, element or cassette which functions as a liquid integrated circuit for moving materials around, mixing, separating and measuring properties of those materials.
A number of different technologies have been applied to the fabrication of these microfluidic devices. For example, initial microfluidic devices were generally fabricated from silicon wafers using photolithographic techniques commonly exploited in the electronics industries. See, e.g., U.S. Pat. No. 4,908,112 to Pace, and Terry et al., IEEE Trans. Electron. Devices (1979) ED-26:1880). In brief, grooves and or depressions are etched into the surface of a first silicon substrate while a second substrate is overlaid on the first, sealing the grooves and depressions to define channels and chambers, respectively, within the device. Glass substrates have also been fabricated in a similar fashion. See, U.S. Pat. No. 5,882,465.
Polymer fabrication methods have also been used in the production of these devices. Specifically, polymeric substrates are provided having grooves fabricated into their surface using, e.g., injection molding techniques, embossing techniques or laser ablation techniques. See U.S. Pat. Nos. 5,885,470 and 5,571,410.
U.S. Pat. No. 5,376,252 to Ekstrom on the other hand describes the use of a flexible gasket or spacer placed between two planar substrates, where channels are defined within the gasket or spacer.
While many of the above-described methods have produced functional microfluidic devices, their exist areas for improving the fabrication process for microfluidic devices, e.g., excessive costs, sensitivity to material defects, and artifacts of fabrication that materially affect the functioning of the device, e.g., channel collapse in polymer substrates, etc.
The present invention generally provides microfluidic devices and methods of manufacturing same, which utilize an intermediate polymer layer into which the microscale structural elements are defined. The intermediate polymer layer is typically deposited between two planar substrates, and portions of the layer are removed to define the microscale structural elements of the device. Preferred polymer layers are either photoimagable or are laser ablatable.
A further aspect of the present invention is a method of manufacturing a microfabricated channel network. The method includes providing a first planar substrate having a first surface. A first polymer layer is deposited on the first surface of the first substrate. A first portion of the polymer layer is removed to expose an area of the first surface of the first substrate. Removal of the first portion of the polymer layer provides one or more grooves in the polymer layer that correspond to a desired channel pattern. A second planar substrate layer is overlaid on the polymer layer to seal the one or more grooves in the polymer layer as one or more channels in the desired channel pattern.
Another aspect of the present invention is a microfluidic device, comprising a first substrate layer having a first surface. There is a first photoimagable polymer layer on the first surface of the first substrate. The photoimagable polymer layer has at least a first groove disposed therein in a desired location. The device also includes a second planar substrate layer having a first surface. The first surface of the second substrate layer is mated with and overlays the photoimagable polymer layer.
A further aspect of the present invention is a microfluidic device, comprising a first substrate layer having a first surface. There is a first polymer layer on the first surface of the first substrate. The polymer layer has at least a first groove laser ablated entirely through the polymer layer in a desired location without affecting the first surface of the first substrate. There is also a second planar substrate layer having a first surface. The first surface of the second substrate layer is mated with and overlays the photoimagable polymer layer.
The present invention also provides for an analytical system, comprising a microfluidic device. The microfluidic device is comprised of a first substrate layer having a first surface with a first photoimagable polymer layer on the first surface. The photoimagable polymer layer has one or more grooves disposed therein in a desired location. The device also includes a second planar substrate layer having a first surface. The first surface of the second substrate layer is mated with and overlays the photoimagable polymer layer, sealing the one or more grooves to define one or more microscale channels. The system also includes a material transport system for directing movement of material through the one or more microscale channels and a detector for detecting signals from the material.